I've had this thing forever, always wondering what it is? I think it's an old Mauser sling, but not sure... but it looks like some other Mauser slings I've seen in pics, but pics on the net usually suck and I can't tell for sure, especially on the buckle. Which this one is brass, crudely made as in something very old. Argentine Mauser maybe? The leather part is 41" from where it takes off at the center of the buckle to where the leather folds over at the stud end, which is about another two inches of leather.
Buckle details in these pics should help get this narrowed down.
Thx much in advance for the help ;-)